Yet Another AW4 Transmission Problem

[joe_peters]

Welcome to !

As Kastein said, always start with your BASICS--year/engine/transmission--any info that may be related to your problem such as lift, recent work, etc. This keeps those that want to help from having to post asking for the info. Even if you think it doesn't matter--very generic--it usually does make a difference.

Always describe the symptoms as best you can. "It overheats" is not very useful if it only overheats while sitting in the Jack in the Box drive through. Be as clear as you can in your description. Its Ok if you don't know the exact terminology for a part.

 

[TenthA86]

Fighting a similar problem - looking for ideas.

'89 Cherokee Pioneer 4.0 w/ AW4 & 231, 180k miles - bone stock.

This unit suddenly started slipping (no warning noise, smell, etc) - acts like it's in neutral - lost all power. When cold, it'll start & run OK, but 1/2 mile or less it slips & ceases to engage. Checked fluids, TPS (replaced 90 days ago), reset adjustment on throttle linkage cable, disconnected TCM under dash - still slipping shortly after startup. No tranny fluid leaks, appears to be proper fluid (has run 20k miles without a change or need for add'l fluid) Engine starts OK, no stumbles or hesitations. Occasionally revs a little when started (up to 2k RPM), then drops down as normal. I can shut it down & restart immediately, sometimes can drive 500 yards before it slips again.

It's my daughter's jeep - and both she & I are too broke to send it to AAMCO where a full rebuild seems to be their first suggestion.

 

[kastein]

Does reverse still work when it starts slipping in drive?

 

[TenthA86]

negative - nothing works - forward, reverse, manual shifting or 4WD

but when I re-start, everything works OK until it fades out again.

 

[joe_peters]

Ok--automatic transmission is wholly dependent on the ATF to function. Without it, slush box no move the vehicle.

Now, "proper fluid" as in Dex III/Mercon? Ok, IF THE TRANSMISSION NEVER OVERHEATS that fluid is maxed out at 30k miles and should be flushed and replaced. Heat kills transmission fluid, and I'm willing to bet yours is kaput. Of course, it doesn't cost me anything to make that bet, and even if I lose I'll likely welsh on the wager so tough.

Seriously, I would buy 13-14 quarts of the cheapest Dex III around and do a poor man's flush while keeping your fingers crossed.

 

[kastein]

Agreed... though it sounds almost like you are low on fluid to me. Are you on a perfectly level surface when you check it? Does it still feel slightly "grippy" when you put it on your fingers and rub them together?

 

[DWRDodge6.7]

In my experience with 5 XJs and 2 ZJs and a host of other Mopars, is that the AW4 is the most forgiving of the electronic transmissions offered by Mopar. I have run Dexron Mobil ATF and Mopar ATF+, 3 & 4 in the AW4s that I have owned. The '98 XJ that I use as a DD has had Mobil in it since it was new and is now at 200,000 KMs. It towed a trailer for several years, and did some serious offroading for several years with no problems.
The 42, 44, 46, 47 and 48 RE series Mopor transmissions on the other hand are very fluid sensitive. They require ATF+3 or 4 to function properly. The use of other synthetics and Dexron or any blend can and usually will promote slippage, and poor shifting. These transmissions also require servicing which includes band adjusting. They are great transmissions but require more attention than the AW4.
ATF+4 is a synthetic fluid that replaced ATF+3 which was a semi/blended synthetic fluid.

 

[TenthA86]

I may try the flush & fill routine, but can't understand the sudden onset, nor the occasional working - then not working - symptom. I haven't added any fluid to this tranny (no leaks) in 20k miles, so don't know brand or history.

Tranny is on a slight incline when checked (nose up) and fluid feels normal, but will try a drain & filter to see what works this weekend. Wish me luck...

 

[TRCM]

Fighting a similar problem - looking for ideas.

'89 Cherokee Pioneer 4.0 w/ AW4 & 231, 180k miles - bone stock.

This unit suddenly started slipping (no warning noise, smell, etc) - acts like it's in neutral - lost all power. When cold, it'll start & run OK, but 1/2 mile or less it slips & ceases to engage. Checked fluids, TPS (replaced 90 days ago), reset adjustment on throttle linkage cable, disconnected TCM under dash - still slipping shortly after startup. No tranny fluid leaks, appears to be proper fluid (has run 20k miles without a change or need for add'l fluid) Engine starts OK, no stumbles or hesitations. Occasionally revs a little when started (up to 2k RPM), then drops down as normal. I can shut it down & restart immediately, sometimes can drive 500 yards before it slips again.

It's my daughter's jeep - and both she & I are too broke to send it to AAMCO where a full rebuild seems to be their first suggestion.

Check all electrical connections and also alternator/battery conditon.

I had a very similar issue happen, and it was because the alt died, and killed the battery. Batt volt got too low, and the trans, being electrically controlled, started slipping very badly, in all gears.

Worth a shot to check it all out.

New alternator & battery and it has run great with nothing else being done for the last 4 yrs.